1. Field of the Invention
The invention relates to automotive power supply systems and methods of operating the same.
2. Discussion
Different techniques may be used to heat a battery. As an example, U.S. Pat. No. 7,234,552 Prema et al. discloses a method for heating a battery in a hybrid electric vehicle. The method includes determining a battery temperature and determining whether a tip-in event, a tip-out event, or a terminal voltage event has occurred. The polarity of the battery is reversed if the battery temperature is below a predetermined value and if a tip-in event, a tip-out event, or a terminal voltage event has occurred.
As another example, U.S. Pat. No. 6,441,588 Yagi et al. discloses a battery charging control method. The method includes executing a first pulsed charging and discharging operation when a battery temperature is lower than a first predetermined temperature. During the first pulsed charging and discharging operation, the amount of charging is equal to the amount of discharging. The method also includes switching from the first pulsed charging and discharging operation to a second pulsed charging and discharging operation when the battery temperature exceeds the first predetermined temperature. During the second pulsed charging and discharging operation, the amount of discharging is less than the amount of charging. When the battery temperature exceeds a second predetermined temperature, a normal charging operation is performed.
As yet another example, U.S. Pat. No. 6,002,240 McMahan et al. discloses a rechargeable battery pack that can sense when it is exposed to a harmful low temperature and cause a heating circuit to heat the battery pack so that it remains in a temperature regime compatible with normal operation.